Verification of ICON/MIGHTI wind by comparison with meteor radar wind: Effect of airglow on ICON/MIGHTI wind observations

The Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) onboard the NASA Ionospheric Connection Explorer (ICON) has retrieved neutral winds at altitudes of 88 km ~ 300 km with limb-scanning using the OI green line (557.7 nm) since November 2019. Neutral winds measured by MIGHTI are helpful information for studying the dynamics in the thermosphere and mesosphere. On the other hand, it is essential to verify the wind data from MIGHTI, which is a relatively new and most up-to-date instrument, using reliable data such as wind from a meteor radar. This study compared winds at altitudes of 91 km and 94 km over the Korean Peninsula measured from 2020 to 2021 by two instruments: the MIGHTI and the meteor radar operated by the Korea Astronomy and Space Science Institute (KASI-MR). We found that the MIGHTI and MR winds were generally similar at night, but there was a significant discrepancy between the two winds during the day. To understand why the two wind measurements are similar at night and differ significantly during the day, we investigated the maximum altitude and slope of the green-line airglow. As a result, it was confirmed that the effect of airglow on the limb scan of the MIGHTI, that is, the vertical difference in airglow emission during day and night, is one factor contributing to the nighttime similarity and daytime discrepancy between the MIGHTI and KASI-MR winds. Therefore, especially when using the daytime MIGHTI wind, it is suggested that special attention is required in using it, recognizing that the effect of this factor is included.